1. Field of the Invention
The invention relates to a device for controlling at least one valve of an internal combustion engine, especially the gas supply value of a gasoline engine, which can be operated by a piston of a working cylinder that can be pressurized by a pressure medium, preferably against the return force of a spring, before which, on the pressurization side, a control device is arranged, preferably in the form of a control slide valve. The control device has a movable control apparatus, which can be used to pressurize a steam space of the working cylinder with the pressure medium for the purpose of opening the valve and to relieve the pressurized space for the purpose of closing the valve. The control apparatus itself can be controlled by means of an associated pilot control device.
2. Description of the Prior Art
German reference DE 43 03 299 A1 discloses a control system of this type for the gas supply valve of a gasoline engine. In the disclosed system, a control device in the form of a control slide valve can be deflected against the return force of a spring, which is arranged above the control slide valve in a cylinder that accommodates the control slide valve, as the result of pressurization, which is initiated by a pilot control device, of a surface of the control slide valve in the axial direction of the control slide valve. In this way, a high-pressure hydraulic line is connected to a working space of a working cylinder, so that the piston arranged in this working space and connected to the gas valve is subjected to high pressure and deflected against the force of a return spring. In the pilot control device, the hydraulic pressure is connected to a pressure line that leads to a surface of the control slide valve. This connection occurs as the result of the deflection of a piston, which has a control recess and is controlled by a camshaft and operates the control shaft that controls the inlet valve of the gas engine. The stroke of the piston can be set by turning a lever that is located on a working cylinder of the piston connected to the gas supply valve. The duration of opening can be set by turning a lever that is arranged on the pilot control device and connected to a pilot-control-device piston, which pressurizes a surface of the control slide valve via a control recess. In this arrangement, the opening timepoint and the closing timepoint of the controlled gas valve cannot be adjusted independently of each other or independently of the control exercised on the inlet valve of the internal combustion engine.
German reference DE 31 35 650 C2 discloses an arrangement that permits adjustment of the opening duration of an inlet valve for an internal combustion engine. The arrangement has a cam seated on a shaft, which deflects a piston. The piston is connected to a second piston, which in turn is connected to the inlet valve, via a hydraulic column enclosed in the normal state.
In order to close the inlet valve while the first piston is still deflected by the cam and thus to adjust the opening duration of the inlet valve, the hydraulic fluid between the two pistons can be released. When this happens, the lower piston, which is connected to the inlet valve, is returned by a return spring, so that the inlet valve closes.
To allow the hydraulic fluid to emerge from the space between the two pistons, there is a valve actuator that in the normal state blocks a recycling line for the hydraulic fluid. The extension of the valve actuator is clamped between a piezoelectric column and an anvil and is held in this position by means of a pressure spring. In order to shorten the opening duration of the inlet valve by releasing the recycling line, the extension of the valve actuator can be released by the application of a voltage signal to the piezoelectric column, so that the valve actuator is moved against the force of the return spring by means of the pressure available in the deflected state of the pistons and the recycling line is released, so that hydraulic oil can flow out between the two pistons, so that the second piston, moving relative to the first piston, can move back, due to the return force of a spring arranged within it, and close the inlet valve.
When the first piston returns to the non-deflected state, the pressure drops between the two cylinders, so that the valve actuator, due to the return force of its return spring, returns to the normal position that closes the recycling line for the hydraulic fluid, where, by interrupting the voltage applied at the piezoelectric column, it can then be clamped between the column and the anvil. Via a back-pressure valve, the space between the two pistons can be refilled with hydraulic fluid from a supply area for hydraulic medium.
This arrangement permits only the opening duration of the inlet valve of an internal combustion engine to be controlled.
U.S. Pat. No. 2,602,434 discloses an arrangement for controlling the start of opening and the stroke of an inlet valve for an internal combustion engine. A lever is provided to control when the inlet valve starts to open. By turning this lever, it is possible to turn an opening-time control edge, which runs obliquely to the axial direction of a piston that can be deflected by a cam. In order to limit the stroke of another piston connected to the inlet valve, another lever can be used to turn a control edge, which is located on the piston in question and opens a relief line to a pressure medium reservoir.